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Ignition of methane-air mixtures by laser heated small particles.

Authors
Dubaniewicz-T; Cashdollar-K; Green-G; Chaiken-R
Source
J Loss Prev Process Ind 2000 May; 13(3-5):349-359
NIOSHTIC No.
20022694
Abstract
Optical technologies have progressed rapidly in the past 15 years. One application of laser technology in underground coal mines currently under evaluation is the remote measurement of explosive methane gas. Federal regulations require that atmospheric monitoring systems used in gassy underground mines where permissible equipment is required shall be intrinsically safe. Mine Safety and Health Administration criteria for the evaluation and test of intrinsically safe apparatus and associated apparatus contain no specific guidance for optoelectronic components such as diode lasers. The National Institute for Occupational Safety and Health is conducting a study to help provide a scientific basis for developing appropriate safety guidelines for optical equipment in underground coal mines. Results of experiments involving ignition of methane-air mixtures by collections of small heated particles of Pittsburgh seam coal and black iron oxide are reported. The inert but more strongly absorbing iron oxide targets consistently ignited methane-air mixtures at lower powers than the coal targets. Minimum observed igniting powers for laser energy delivered by 200, 400 and 800 um core fiber opticcables and directed onto iron oxide targets in methane-air atmospheres were 0.6, 1.1, and 2.2 W, respectively. Comparisons to results of other researchers are made. A thermal layer theoretical approach to describing the process is included as an appendix.
Keywords
Hazards; Lasers; Methanes; Coal-mining; Optics; Iron-oxides; Underground-mining
Contact
National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, P.O. 18070, Cochrans Mill Road, Pittsburgh, PA 15236-0070
CODEN
JLPIE9
Publication Date
20000501
Document Type
Journal Article
Email Address
tcd5@cdc.gov
Fiscal Year
2000
NTIS Accession No.
NTIS Price
Issue of Publication
3-5
ISSN
0950-4230
NIOSH Division
PRL
Source Name
Journal of Loss Prevention in the Process Industries
State
PA
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